The organic electroluminescent element (hereinafter, also referred to as an “organic EL element”) is a type of the light-emitting element that emits light by applying a voltage. At present, light-emitting devices such as an illuminator and a display device which use the organic EL element as a light source are being put to practical use and brought to the marketplace.
An organic EL element generates heat during use, and the temperature thereof increases. Because bringing an organic EL element into a high temperature during use leads to accelerating degradation of the element, various properties of the element are degraded. For example, a luminance half-life period of the element becomes shorter. Therefore, in order to lower a temperature during use, various measures for heat dissipation are being studied.
An organic EL element is usually provided on a supporting substrate, and further a sealing substrate or a sealing film for covering the organic EL element is provided on the supporting substrate. Between the organic EL element and the sealing substrate, a predetermined gap is provided. When the gap is filled with a predetermined gas or is in vacuum, because heat conduction from the organic EL element to the sealing substrate is poor, there is a problem that heat generated in the organic EL element cannot be efficiently dissipated from the sealing substrate. In order to improve heat conduction from the organic EL element to the sealing substrate, a device was proposed in which a heat conducting member having better thermal conductivity than a predetermined gas is provided between the sealing substrate and the organic EL element (for example, see Document 1).